CVE-2026-5950

Summary

An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Affected Software

VendorProductVersion RangeStatus
ISCBIND 99.18.36 <= 9.18.48affected
ISCBIND 99.20.8 <= 9.20.22affected
ISCBIND 99.21.7 <= 9.21.21affected
ISCBIND 99.18.36-S1 <= 9.18.48-S1affected
ISCBIND 99.20.9-S1 <= 9.20.22-S1affected

Weaknesses

  • CWE-606: CWE-606 Unchecked Input for Loop Condition

Workarounds

No workarounds known.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References